1. Field of the Invention
The present invention relates to systems for treating wastewater and, more particularly, to wastewater treatment systems that are modular in design.
2. Description of the Prior Art
Treating wastewater is important for a number of reasons. As the world's population grows, the amount of water needed for consumption and other use continues to increase, while the amount of naturally available water remains the same. Thus, there is an ever increasing demand for usable, clean water, making the reclamation of tainted water extremely important.
In addition, as existing metropolitan areas become more crowded, developers are encouraged to construct new housing in previously undeveloped areas. Many such areas lack sufficient water for consumption, irrigation and similar purposes, necessitating the reclamation and reuse of available water resources.
One source of potentially reclaimable water is sewage from the residential use of water, commonly referred to as wastewater. Residential wastewater has a high water content, but requires substantial processing before it can be reused because of the human waste and other contaminants mixed with it.
A number of different systems have been proposed for treating sewage or wastewater. One such system, disclosed in U.S. Pat. No. 2,528,649, incorporates a simple sedimentation tank for separating solid waste, or "sludge", from water. The sludge is then passed to a digestion system where it is allowed to settle so that clear aqueous liquid separates from the sludge. The clear liquid is redirected back to the sedimentation tank. Unfortunately, this system suffers from a number of shortcomings that make it inefficient. First, the system makes no provision for increases in the volume of incoming sewage, either during high flow periods or as a community expands and therefore creates a larger amount of wastewater. In time, another complete treatment system would be required to handle the additional wastewater, resulting in unwanted expenses for the community. The system also incorporates a relatively crude sedimentation tank that merely allows the influent sewage to separate and does not aerate or facilitate processing of the sewage in any other way.
Another wastewater treatment system, described in U.S. Pat. No. 3,679,053 to Koulovatos et al., has three processing tanks for, respectively, receiving, aerating, and settling influent raw sewage. This system also fails to account for the possibility that the amount of influent sewage will increase over time. In addition, the disclosed system provides no overflow protection in case of large transient increases in the amount of sewage to be treated.
Yet another wastewater treatment system is disclosed in U.S. Pat. No. 3,920,550 to Farrell, Jr., et al. The Farrell system also has an aerobic and settling tank for aerating wastewater, and includes a sludge tank for receiving and further processing sludge separated from the supernatant water. However, it makes no provision for increases in the quantity of wastewater as a developing community expands. In addition, there is no disclosure of a plurality of parallel treatment tanks, nor of a system for controlling the operation of such tanks.
Accordingly, there is a need for a wastewater treatment system designed to accommodate increasing quantities of wastewater without requiring that an entirely new system be built. In addition, a need exists for a sewage treatment system that is designed and operated to be energy efficient. The present invention addresses these needs and others.